“…where Equation ( 14) represents the strain compatibility, being ∆ε p and ε p the strain by imposition of the prestressing system and the strain of the prestressing strand, respectively, and Equation ( 15) represents the stress-strain relation for the prestressing steel, being f yp and E p its yield stress and elastic modulus, respectively. In summary, for a given value of tensile principal strain in concrete, ε 1 , where such strain works as an input parameter, the shear model for the prediction of the load-deformation behavior of a prestressed concrete beam is based on the nonlinear system of Equations (3)(4)(5)(6)(7)(8)(9)(10)(11), with to 10 equations (notice that Equation ( 13) is actually two equations in turn) in the 10 unknowns (θ, ε x , ε t , ν, ε 2 , σ 2 , σ s,x , σ s,t , ε p and σ p ).…”